Electric heating device.



J. I. AYER & H. B. GALE.

ELECTRIC HEATING DEVICE. APPLICATION FILED JUNE 13,1908.

Patented Nov. 24, 1908.

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8 Ii pg V 16%06656/6. W AM JAMES I. AYER, OEF CAMBRIDGE, AND HOR ACE B.GALE, OF NATIGK, MASSACHUSETTS,

ASSIGNOBS 'lO SIMPLEX ELECTRIC HEATING COMPANY, OF CAMBRIDGE, MASSACHU-SETTS.

ELECTRIC HEATING DEVICE.

Specification of Letters Patent.

Patented Nov. 24, 1908.

Application filed June 1a, 1908. Serial no. 438,299.

To all whom it may concern:

Be it known that We, JAMES I. AYER and Homer B. GALE, citizens of theUnited States, and residents of Cambridge and Natick, respectively, bothin the county of Middlcsex and State of Massachusetts, have invented anImprovement in Electric Heating Devices, of which the following description, in connection with the accompanying drawings, is aspecification,like letters on the drawings representing like parts.

Our invention is an improvement on the primary invention set forth in00- ending application Serial No. 438,103 filed une 12, 1908, in whichthe general purpose and nature of the invention are set forth, thepresent improvement having for its object the still further increase ofheating capacity and uniform distribution of the heat, for a givenweight or size of apparatus.

Stated in general terms, this type of invention consists of so disposingthe resistance wire withrelation to the heat receiving or absorbingsurface, which is parallel to the'plane 0 the resistance wire or ribbon,as greatly to increase the available surface area both of the resistancemedium and of the heat-absorbing medium over that which is ossible whenthe resistance medium'is lai flat upon a single plane or horizontalheat-absorbing surface, in the manner common in electrically heatedtools and apparatus.

The desired result is secured by standing at ribbon-like layer ofresistance wire or the like on edge substantially perpendicularly to thegeneral plane of the heater, the latter being provided withcorresponding grooves in which the edgewise-standing resistance 40 wireis immovably secured by vitreous enamel fused to the --iron or metalconstitutmg the heat-absorbing medium and also fused about the wire,thereby holding the latter in'an extended flat layer or plane ver andyet a very much tical to the main body of the iron and yet parallel tothe heat-absorbing surfaces or walls of said grooves. By maintainingthis extended 'flat layer of resistance medium thus parallel or at'auniform distance at all points from the heat-receiving surface, auniform rate of absorption of heat is insured ater length of heatingunit is made ossi le, so that less stress or strain results or a givenlength of wire, inasmuch as the desired temperature of the tool ismaintained through the agency of a much longer resistance wire thanbefore. Inother words, for a given mass of heat absorbing and conveyingplate or tool, the

samequantity of heat as before is derived from a greater length of theresistance wire than before, and hence the latter is subjected to lessstrain inasmuch as there is obviously a lower temperature per givenlength of wire, and yet notwithstanding thls fact there is no irregular.heating of the wire (such as would occur if the wire were wound in acoil or in any form which would place any part of the wire further fromthe plate than any other part) because all portions of the laterallyextended or ribbon-like layer of said wire are at practically the samedistance from the heat-receiving and absorbing 7 surface of the plate. 0

Our present improvement consists in arranging the widely extendedribbon-like layer of resistance wire or current-conveying medium in areflex form, 2'. e. in a V shape or U shape, viewed in cross section,the receiving grooves of the plate being correspondingly shaped, and theintervening ribs or projecting portions of the plate having their sidesor heat receiving and absorbing surfaces arranged parallel respectivelyto the adjacent sides of the reflex windmg of wire. By this means wesecure the advantages of the main invention with 1ncreased efliciency ofresults.

Our invention also has advantages of manufacture, durability and use.

.view showing the coverin layer of enamel applied, thereby immovabyembedding theresistance in operative positlon; F 1gs. 6 and 7 are planand end views respectively of a ribbon of resistance wi're bentflatwise; Fig. Y

8 being an end view of the same reflei red or bent into V shape,according to our inven- 1 and retain thus in proper operative positionthe conductor which is to I venient type of this general classofelectrically heated tools and devices, and accordingly it will beunderstood tha' I this 'ispresented merely as a type and that it doesnot limit the invention in any way. This block' or plate is providedwith a series of grooves 2 and intervening ribs or lateral projections 3standing approximately perpendicular to the main plane or body 4 of theblock orplate. Preferably the heat-receiving sur faces 5 of thesegrooves and ribs are flared slightly from each other into V shape as.shown. -The resistance conductor is first bent or otherwise shaped inribbon like form as shown at 6, Fig. 6, and at 7, Fig. 9, the articulararrangement of the successive ben s or turns of the winding being immaterial so long as the general object is secured of having as great alength as possible of wire all lying in one-and the same plane,

i. e. arranged in ribbon-like form. This rlbbon or winding is thencreased or reflexed down its'middle as shown in'Figs. 8'

and 9 so as to present opposite .approzdmately parallelupwardly-extending legs or fiat portions 8. If the grooves have theirsides flaring, these portions 8 of the reflexed winding willcorrespondingly flare, or in other words the ribbon-like winding is bentor reflexed to correspond to the shape of the ooves' so as to maintainthe leg portions n planes-parallel to the heat r ceivlng and absorbingsurfaces of the ribs or walls of the grooves. Having thus formed thewind- I {place as shownin-Fig. 4, and thereupon a:

fused enamel covering 10 or other suitable 'iililg, a layer'9 of enamelor other suitable in ting medium is fused orotherwise applied as apreliminary:l coating-to the iron .or metal constituting t e object tobe heated, i. e. to the late 1 inthe illustration of the drawings, t ereflexed ribbon is then put'ininsulating coating is applied so as toembed- ;convey'the electric current for heating the icon or plate 1.

It will be understoed'that any usual -or- 60 preferred means ofretaining and embedding ,the resistance wire may be availed of. It

also ,be understood that we are not limited in any way to the particularshapes of ribbon-like arrangements of the windmfgflgr e formofthegrooves, or general shape 0 plate or tool, inasmuch as these are allcapable of a wide variety of embodiments within the skill of thoseversed in the art, without departing from the spirit and scope of ourinvention. It will also be understood that theplate has transverse endgrooves 11, 12 for receiving the wire at the ends, and in eneral thearrangement of the grooves may be varied according to the requirementsof the particular tool or device or the preference of the particularconstructor, The form shown in Fig. 1 is preferred because of itssimplicity and the facility with which the wires may be placed-andembedded.

From the above description it will readily be understood that when thecurrent is turned on, the resistance wire throughout its greatlyincreased extent conveys from all points thereof uniformly to theadjacent re ceiving surfaces of the ribs 3 the same amount of heat, andinasmuch as the wlre is in ribbon-like formation and standssubstantially perpendicular to the general extent or plane of the plate1 there 1s a greatly increased -length of wire over that which would bepossible if the wire were laid in the usual horizontal: windin on theusual horizontal surface or top ,0 the plate or metal constituting theobject to be heated. In

other words, our invention provides a large surface parallel to the faceof the conductor, insuringthe uniform and rapid absorption of heat atall points, said large surface being much greater in area than the planeor horizontal area of the plate or object to be heated. By this meansthe exposure of the' generating surfaces of the ribbon-like winding is.radically increased and the uniform absorption of heat therefrom ismuch greater than could occurby equivalent resistance applied to theflat surface of the heater in the ordinary manner.

Having described ourv invention, what we claim as new and desire tosecure by Letters Patent'is'r I 1. In an electric heater, aheat-absorbing body provided with 'aseries of grooves, and

ribbon-like current conductor secured in sald grooves, said ribbon-likeconductor being creased "longitudinally and havin its re-' ios flexedsides held substantially para el to the walls of said grooves.v I

2. In an electric he ter, a heat-absorbin body provided with a series-ofgrooves, an

ribbon-like current conductor secured in' said grooves, said ribbon-likeconductorbeing" creased longitudinally and having its reflexedsides-held substantially parallel to thewalls of said grooves, saidribbon-like con-"- ductor containing in I its length a-series ofwidthwise turns,"providing a correspondlength of the ribbon-likeconductor.

3. In an electrlc heater, a-.heat-'abs'orb in body provided with aseries of grooves, an

inglydongc'r path for the current than the a conductor, V-shaped incross section, permanently secured in said grooves with vitreous enamel,the sides of the conductor being embedded in the enamel a proximatelyparallel to the adjacent walls 0? the grooves.

In testimony whereof, we have signed our names to this specification, inthe presence 20 of two subscribing witnesses.

JAS. I. AYER. HORACE B. GALE. Witnesses:

ELIZABETH M. \CIONLIN, DORA A. Pnoc'ron.

